US Democratic front-runners Hillary Clinton and Barack Obama have traded accusations over a photo of Mr Obama circulating on the internet.

The picture, sent to the Drudge Report website, shows Mr Obama wearing traditional Somali dress during a visit to Kenya in 2006.

The website said it was circulated by Mrs Clinton's staff but her team denied they had sanctioned its release.

The row comes as the rivals campaign for two crucial primaries next week.

Analysts say Mrs Clinton needs to win the contests, in Texas and Ohio, to remain in the race to choose the Democratic candidate for November's presidential election.

With tempers fraying ahead of a crucial debate in Ohio on Tuesday, the former first lady highlighted Mr Obama's lack of foreign policy experience during a speech in Washington.

Reminding the George Washington University audience of her own international credentials, Mrs Clinton suggested her rival would need a "foreign policy instruction manual" to keep the country safe if elected.

Fear-mongering

The photograph published on Monday shows Mr Obama - whose father came from Kenya - wearing a white turban and a white robe presented to him by elders in the north-east of the country.

Dirty tricks or a fuss about nothing? Here in Team Obama they are taking it very seriously